The present invention is directed to bicycle computers and, more particularly, to a pseudo crank speed arithmetic unit for a bicycle wherein the pseudo crank rotational speed is computed assuming that the crank is being rotationally driven at a rate that would sustain the traveling speed of the bicycle.
There are known bicycle computers for digitally displaying various bicycle data, such as the speed of the bicycle, the distance traveled, lap times, crank spindle torque, the shift position of the change gear device, the pulse rate or blood pressure of the rider, and so on.
Frequently, the crank of the bicycle is not rotationally driven when the rider is coasting or going downhill. If the rider thereafter wants to resume pedaling by pressing on the stationary pedals and turning the crank, no-load rotational drive will result as long as the rotational speed at which the crank is actually driven is lower than the travel speed. Accordingly, the rider usually wants to resume pedaling at least fast enough for the rotational speed of the crank to match the travel speed of the bicycle. However, when the bicycle is coasting or going downhill and the rider tries to press the stationary pedals and turn the crank, he or she has no idea how fast to pedal. If the rider misjudges the crank rotational speed, then there will be a time loss until the point when the crank is actually driven.
The magnitude of the rotational torque at which the crank is driven is determined to a certain extent by the muscle power (such as that of the legs) of the bicycle rider, and a gear ratio that matches the rider's muscle power is determined when the rider selects the front gear and the rear gear. Thus, once the desired travel speed of the bicycle is set, the gear ratio determines the optimal crank rotational speed for that rider's ability. When the bicycle is moving so fast that the rotational speed of the crank used before coasting or proceeding downhill is no longer proper, the rider needs only to make a gear change in order to find the optimal pedal speed. However, since there is no criterion for selecting this gear change, quite a bit of experience is needed to select the optimal gear ratio.